This invention relates to electrostatographic reproduction machines, and more particularly to a development unit for use in an electrostatographic reproduction machine. Specifically this invention relates to such a development unit including a blade with a translating tribocharging blade.
Generally, the process of electrostatographic reproduction, as practiced in electrostatographic reproduction machines, includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the photoconductive surface is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. Two component and single component developer materials are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triobelectrically thereto. A single component dry developer material typically including toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a "hardcopy" of the original image.
It is well known to provide a number of the elements and components, of an electrostatographic reproduction machine, in the form of a customer or user replaceable unit CRU. Typically such units are each formed as a cartridge that can be inserted or removed from the machine frame by a customer or user. Reproduction machines such as copiers and printers ordinarily include consumable materials such as toner, volume limiting components such as a waste toner container, and life cycle limiting components such as a photoreceptor and a cleaning device. Because these elements of the copying machine or printer must be replaced frequently, they are more likely to be incorporated into a replaceable cartridge as above.
There are therefore various types and sizes of cartridges, varying from single machine element cartridges such as a toner cartridge, to all-in-one electrostatographic toner image forming and transfer process cartridges. The design, particularly of an all-in-one cartridge can be very costly and complicated by a need to optimize the life cycles of different elements, as well as to integrate all the included elements, while not undermining the image quality. This is particularly true for all-in-one process cartridges to be used in a family of compact electrostatographic reproduction machines having different volume capacities and elements having different life cycles.
In single component development as described above, the particle of toner is charged prior to development of the toner onto the photoreceptive drum by rubbing the particle between a charge-metering blade and the magnetic roll. The charged particles on the periphery of the magnetic roll are then transferred onto the photoconductive drum at the charged portions of the surface of the photoconductive drum or the latent image to form the developed image on the photoconductive drum. The developed image is then transferred onto the substrate or paper.
Referring now to FIG. 2, a typical prior art printing machine 1 is shown. To describe the electrphotogaphic process in greater detail, the imaging cycle of the printing machine 1 begins with a photoconductive drum 2. The drum 2 rotates in the direction of the arrow, and is charged by a charging device A. The charged portion of the drum 2 is then rotated to an exposing station B where either a light lens system or a raster optical scanner forms a latent image on the drum 2. The latent image corresponds to an image of a document positioned on a platen (not shown) or to output which is sent to the raster output scanner.
The portion of the drum 2 bearing the latent image is then rotated to the developer station C where the latent image is developed with developer material such as with charged single complement magnetic toner using a magnetic developer roll 4. A regulating member in the form of, for example, a regulating blade 7 is closely tangential positioned to the periphery of the drum 2 and is utilized to control the amount of toner on the drum 2.
The developed image on the drum 2 is then rotated to a near vertical transfer point at transfer station D where the toner image is transferred to a copy sheet fed along a copy sheet or substrate path. The copy sheet substrate with the transferred toner image is then directed to the fuser station E where the heated fuser roll 5 and pressure roll rotate to heat, fuse and fix the toner image onto the copy sheet substrate. The copy sheet substrate then, as is well known, may be selectively transported to an output tray (not shown) or to another post fusing operation.
The portion of the drum 2 from which to developed toner image was transferred is then advanced to the cleaning station F where residual toner and residual charge on the drum 2 are removed by for example a blade 6. The imaging cycle of the machine 1 using the drum 2 can then be repeated for former transferring another image as the clean portion of the drum 2 again comes under the charging station A.
The quality of the print copy from the printing machine is affected by many factors. One of these factors is the amount and evenness of the layer of toner on the periphery of the drum 2. Another related factor is the amount and evenness of charge on the toner around periphery of drum 2. A non-uniform layer and/or a non uniform charge on the periphery of the drum results in streaks in the copied sheet and particularly in non-uniformity in the solid areas.
The regulating blade 7 is primarily responsible for these factors. One reason that the evenness of the letter of toner and the evenness of charge on the toner may be nonuniform is that the regulating blade may be worn.
Wear on the blade 7 is inevitable in that the blade must be made from a material which will not damage the periphery of the drum. Since the drum 2 is made of a delicate material, the blade 7 must be made out a material which is non-abrasive to the drum and such a material may wear rapidly.
The following disclosures may be relevant to various aspects of the present invention: